docs: release 1.4.0

Author: tpetry

CHANGELOG.md

@@ -5,6 +5,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.4.0] - 2024-08-29
+### Added
+* `IS NULL` and `IS NOT NULL` conditions
+
 ## [1.3.0] - 2024-05-31
 ### Added
 * `Cast` language construct